Method of growth control and carrier



Patented June 2, 1942 UNITED STATES I 2,284,970 PATENT OFFICE ammoma'rnon or Gmow'rn CONTROL AND cmma George S. Avery, In, New London,Conn, asslgnor to The Dow Chemical Company, Midland, Mich, a corporationof Michigan No Drawing. Application May Serial No. 337,111

13 Claims.

- This invention relates to the regulation of the development of anabscission layer in growing plants by treatment with an auxin, and moreespecially to a carrier for the auxin which upon drying will form aprotective coating so as to insure that the auxin will be absorbed bythe plant.

The present application is a continuation-inpart of copendingapplication Serial No. 104,543, filed October 7, 1936. i

It is well known that, at various stages in the growth of plants,abscission layers tend to form. The formation of these layers causes theabscission of buds (bud drop), leaves, flowers and fruit. Abnormallyearly development of abscission layers is frequently prejudicial to thenormal development of the plant and is economically undesirable. Amongthe causes of such abnormal does not include substances which are merelybehavior are unfavorable climatic conditions, re-

duced rainfall, and the like.

For example, it has been found that, where the temperature in the wintertime does not fall to a necessary minimum, there often occurs a failmeetthe buds to develop in certain varieties of plants, and sometimes thereis abscission. of a high percentage of flower and leaf buds on fruittrees, such as the apricot and peach. Climatic plant stimulants orsubstances, such as ammonia or ethylene, which have undesirablevolatility.

As-is taught in the previously mentioned copending application, theauxin material is applied to the plant surface at a time, usually fromand other conditions also cause premature leaf and fruit drop. Theregulation of these conditions is very important in view of large lossessuffered annually by the fruit grower.

Herbaceous plants, such as greenhouse grown sweet peas, are also subjectto bud abscission and leaf drop which prevent the normal development ofthe plants. The regulation of this condition is important.

As disclosed in my co-pending application, Serial No. 336,658, filed May22, 1940, now U, S. Patent No, 2,220,505, the formation of thisabscission layer can be regulated by applying an auxin to the trunk,branches, leaves, flowers, or fruits of growing plants at a timesubstantially in advance oi the period in which the abscission layerwould normally be expected to develop. Either a spray or dustingtechnique may be employed in applying the auxin to the plant. The use ofsprays has been found particularly satisfactory,

- a simple solution or dispersion of the auxin being adequate for thispurpose.

The auxins employed may be auxin B, heteroauxin (3-indoleacetic acid),or similar plant auxins; they may be used either in the chemically pureform, or as an impure plant extract, or an impure extract from urine orother animal materials.

The term auxin includes those substances which cause an enlargement ofthe plant cell as distinguished from those substances that cause plantgrowth by supplying nutrient to the plant. In addition to auxin A and Band heteroauxin, the influence of acids, such as alpha-naphthalene A,auxin.

one day to three weeks in advance of the period when the buds,leaves,.fiowers or fruits might be expected to absciss. Th auxin can beapplied as a spray by simply dissolving or dispersing the requiredamount of auxin in water. This may be accomplished either by adding theauxin, a solution thereof in water miscible organic solvent, or a watersoluble salt of the auxin to the required amount of water to obtain asolution or dispersion of the active material. Similarly the auxin maybe incorporated into dust compositions, any of the common finely dividedcarriers being suitableprovided they do not react with or on the auxinso as to destroy its effectiveness.

The present invention embraces the idea of providing a carrier of a typewhich will hold the auxin in contact with the plant I have found thatthe best carrier, upon drying, should possess the property of forming aflexible, water'insoluble coating so as to protect the auxin, and enablethe plant to absorb the latter at a constant and continuous rate untilthe supply of auxin is exhausted. The dried coating of the carrier-auxinmixture should also be at least semi-permeable so as to permit thebreathing of the plant and not to interfere with normal plantmetabolism. The carrier must also be of a type which is compatible withthe auxin.

In practice, any type of emulsion, dried residues of which have thesecharacteristics, would be satisfactory as a carrier. I have found thataqueous dispersions comprising a waxy material are especially suitable.In preparing such compositions, the wax may be melted and the properproportion of auxin mixed therewith, after which the mixture may becompounded in any suitable manner to obtain the desired aqueous Arepresentative composition in which the auxin may be incorporatedconsists of wax dispersed in aqueous emulsion with a suitableemulsiiying agent, such as soap. Such an emulsion may be obtained bydispersing a wax, such as carnauba wax, in the amount of from about to25 per cent of the composition in an aqueous solution of soap. Sodiumoleate and triethanolamine oleate are suitable as emulsifying agents andmay be used in amounts of from 1 to 8 per cent. Soaps prepared fromother bases. such as potassium hydroxide and ammonia, and other fattyacids, such as linoleic acid, may also be used. The following example isgiven to illustrate a carrier of this type:

Per cent Carnauba wax 23 Sodium and triethanolamine oleate 5.8 Water71.2

The above emulsion may be made as follows:

A mixture of 125 parts of camauba wax is melted with 22 parts of oleicacid at 85-90 C. A solution is made up of 1 pound of caustic soda and 10pounds of triethanolamine in 30 pounds of water, and the solution isheated to 90 C. This solution is stirred ino the wax-oleic acid mixtureat the same temperature and thoroughly mixed to form a jelly-like mass.To this mass water at a temperature of 90 C. is slowly added until atotal weight of 125 pounds is reached. The product is an emulsionsuitable as a protective carrier for the auxin and, if desired, may befurther diluted with water to control the thickness of the coating.Other waxes, such as candelilla., beeswax, paraflin and ceresin may besubstituted in whole or in part for the carnauba. As most auxins areheat stable, the auxin may be added at any point in the procedure.

The ratio of wax to fatty acid in the emulsion may be varied to someextent. Variations in the composition and percentage of the emulsifyingagent affect the surface tension of the emulsion and the waterrepellancy of the film resulting from the use of the emulsion.

The formation of the soap emulsifier internally in the solution, 1. e.(in situ), while in intimate commixture with the material to beemulsified, produces a very efiective emulsion. Moreover, it issometimes advantageous to add to the emulsions alkali metal or theammonium salts of casein, or gums or resins. such as as rosin, shellac,pontianak gum, in amounts of from 5 to 40 per cent of the amount of waxused.

It is preferable that the organic acid from which the soap is formed inthe foregoing compositions be a free fatty r acid or a mixture of freefatty acids rather than a fatty acid glycsired. The following examplesare illustrative of suitable carrier materials: J Per cent (by wt.)Beeswa 5 Refined mineral oil. 25

Oleic acid 1.5 Bora 1 Water 57.5

10 Paraflln w x 7.5 Refined mineral oil 25 Stearic acid 1.5 Bora 1Water- 65 1 space-lo In preparing the above emulsions, the paraffin,mineral oil and free fatty acid are added together to form a liquidmixture which is brought to a temperature well above the solidifyingpoint of its waxy constituent. The water with the borax dissolvedtherein, also heated to approximately the same temperature, is then runinto the hot wax-oil-acid mixture with vigorous agitation which producesa milky emulsion that is water can be added to thin the emulsion. The

eride. The presence of the latter results in the formation of glycerolwhich is not a desirable component of my new compositions.

While any of the alkaline hydroxides, carbonates and borates, as well asorganic bases,

auxin may be added at any point in the procedure.

After the emulsion is applied to the plant, it dries to provide asubstantially uniform filmlike waxy protective coating which is notsticky or tacky, and adheres to the treated surface. At the same time,this coating is gas permeable to such an extent that it does notentirely prevent or unduly interfere with the breathing or transpirationso essential to the continued wellbeing of the plant. The refinedmineral oil specified in the foregoing formulae may be omitted, in whichcase the percentage of paraflln should ordinarily be reducedsubstantially.

As a preferred carrier for the auxin, an aqueous emulsion consisting ofwax and a colloidal earth may be employed, whereby a permeable film isformed. The auxins are given up slowly to the plant and are preventedfrom being washed away by rains at such a rapid rate as to prevent theirdesired action. In one method of preparation, the colloidal earth ismade into a suspension in hot water and molten wax is added to themixture when the latter is at a temperature which is above that of themelting point of the wax. The wax is added with constant stirring and agood emulsion is obtained. After cooling the emulsion, the auxins areadded and the material is then in condition for being sprayed on theplants. The preferred concentration of auxin used in this and thesubsequently described emulsions comprise 3 parts of an auxin, such asalpha-naphthalene acetic acid, incorporated in a million parts by weightof emulsion.

A good spray can be obtained by employing approximately 3 parts ofcolloidal earth, 20 parts of water, 10 parts of wax and 3 parts of theammonium salt of a drying acid and diluting the whole with approximatelyparts of water. A very good carrier can be formed of 6 parts by weightof paraflin wax, 4 parts by weight of beeswax, 3 parts of a colloidalearth, 3 parts of the ammonium salt of a drying acid and 10 to 15 partsof water. The term ammonium salt of a drying acid refers to unsaturatedfatty acids having two or more double bonds in the struc- 'so forth. Thecolloidal earth may be fullers earth or similar clays, but preferablybentonite.

To obtain the composition the ammonium salt of the drying acid isdissolved in hot water; the suspension of a colloidal earth in hot wateris accomplished separately; the solution and the suspension then aremixed, and to this mixture is added the molten wax at a temperatureabove that of the melting point of the wax. Constant stirring shouldtake place until a good emulsion is formed, and this should continueuntil the mixture is cool. The auxin may be then added. Though sincemost auxins are heat stable they can be added before the cooling.

The wax employed is preferably parafl'in wax, but others can be used,such as carnauba, beeswax, etc.

Another mixture which I have found to be satisfactory as a carrier isthat employing ammonium linoleate by weight 3 parts dissolved in 50parts of hot water. is made into a suspension with 50 parts of the hotwater. The solution and the suspension are then added together and whilethe mixture is above the melting point of paraffin, parts of moltenparaflln are poured into the mixture with vigorous stirring, and theemulsion allowed then to cool to room temperatures while continucuslystirring.

The proportion of auxin added to the carrier depends to some extent uponthe type of carrier selected, the type of plant to be treated, and

the climatic conditions. Generally, however, except where otherwisespecified in this application, the auxin is added in a concentrationwithin a range of from 1 .to 10 parts of auxin to 300,000 parts byweight of the carrier. This figure is not meant to be limiting, but Ihave found that too high concentration of the auxin is undesirable.

The emulsion or mixture of carrier and auxin is applied to the plant inany suitable manner. For example, the mixture may be applied by rubbingor dipping, although preferably a carrier is employed which can beapplied by spraying. After application to the plant, the carrier rapidlyforms a flexible coating which protects the auxin and permits the plantto absorb the material until the supply is exhausted.

While certain embodiments of my invention have been disclosed, it is tobe understood that I am to be limited only by the appended claims andthe showing of the prior art, and'that I am entitled to the equivalentsof the steps taken and.

the substances used.

I claim:

1. As a new composition of matter, a water- Three parts of bentonitedispersible wax, emulsion containing an auxin in low concentration,residues of which emulsion dry to form a flexible, weather-resistantsemi permeable coating over surfaces with which they are contacted.

2. As anew composition oi matter, an aqueous emulsion comprising amixture of an auxin and a wax, said auxin being in low concentration anddispersed throughout .the wax.

3. As a. new composition of matter. a waterdispersible emulsioncomprising a low concentration of an auxin, a waxy carrier and anemulsiiying agent, the dried residues oi said emulsion being insolublein water, flexible, weatherresistant and semi-permeable.

4. As a new composition of matter, a waterdispersible emulsioncomprising a mixture of an auxin, wax, and a colloidal earth, said auxinbeing in low concentration, and dried films of said emulsion beinginsoluble in water, tough, flexible, weather-resistant, andsemi-permeable.

5. As a new composition of matter, a waterdispersible emulsioncomprising a mixture of a wax, a colloidal earth, and an auxin in anamount not greater than 10 parts by weight per 300,000 parts of thecomposition.

6. A method of preventing the abscission of a part of a growing plantcomprising treating the plant with an aqueous emulsion compositioncomprising an auxin and a wax-containing carrier at a time substantiallyin advance of the period when the part might be expected to be abscised.

7. A method of preventing the abscission of a part of a growing plantcomprising treating the plant with an emulsion, said emulsion comprisingan auxin incorporated in a carrier of wax and colloidal earth in theproportions of not more than 10 parts by weight of auxin to 300,000parts of carrier at a time substantially in advance of the period whenthe part might be expected to be abscised.

8. A method of preventing abscission of buds comprising treating thebuds with an aqueous emulsion composition comprising an auxin and a waxat a time substantially in advance of the normal period at which thebuds are expected to open.

9. A method of preventing the abscission of a part of a growing plantcomprising treating the plant with an aqueous emulsion comprising a waxand an auxin at a time substantially in advance of the period when thepart might be expected to be abscised, said emulsion residues forming aweather-resistant fllm over the treated portions of the plant which issufficiently permeable to permit the plant to absorb the auxin.

10. As a new composition of matter an aqueous emulsion comprising a lowconcentration of an auxin embodying the naphthalene group, a waxycarrier, and an emulsifying agent, the dry residues of such emulsionbeing insoluble in water, flexible, weather-resistant, andsemi-permeable.

11. As a new composition of matter an aqueous emulsion comprising a lowconcentration of an auxin embodying the indole group, a waxy carrier,and an emulsifying agent, the dry residues of such emulsion beinginsoluble in water, flexible, weather-resistant, and semi-permeable.

12. method of preventing the abscission of a part of a growing plantcomprising treating the plant with an aqueous emulsion compositioncomprising a wax and an auxin embodying the naphthalene group at a timesubstantially in advance of the period when the part might be expectedto be abwised.

13. A method of preventing the abscission of a part of a growing plantcomprising treating the plant with an aqueous emulsion compositioncomprising a wax and an auxin embodying the indole group at a timesubstantially in advance of the period when the part might be expectedto be abscised.

GEORGE s. AVERY. Jr.

